Both the civil sector and the military sector have long used amphibious vehicles of differing design which are distinguished in particular by means of the drives thereof. This is because, due to the greatly differing operating conditions during travel on land and on water, separate drives have to be provided for travel on land and travel on water, for which purpose various driving concepts have been developed in the past.
In the case of amphibious vehicles, use is made, as the land power unit, of the wheel or chain drives known from the land vehicle sector, with chain-driven amphibious vehicles frequently being encountered in particular in the military sector. Said chain-driven amphibious vehicles customarily have a chain running gear and a closed hull composed of armored steel, in which the vehicle crew is accommodated in a manner protected against military threats.
For travel on water, amphibious vehicles are equipped with a separate drive which ensures the necessary propulsion during the floating mode. As water power unit, use can be made of various drives known from the watercraft sector. For example, use can be made of drives which are arranged on the outside of the vehicle and which are arranged in the manner of an outboard motor with an exposed propeller in the rear region thereof and are supplied with power from the interior of the amphibious vehicle. What are referred to as water jet drives or jet drives have also proven successful as water power units. In these drives, the propeller is arranged within a flow duct and is used for accelerating a water jet, via the repelling force of which the required propulsion is produced. In contrast to the drives arranged externally, said drives are generally arranged internally, as a result of which said drives are better protected against mechanical damage, in particular also during travel on land. The power supply in the case of these drives also turns out to be less complicated because of the internal arrangement of the propeller since a shorter and therefore also lighter drive train can be realized as a result.
In the case of military amphibious vehicles which have a protected hull for accommodating the vehicle crew, the arrangement of such water jet drives in the interior of the vehicle has proven problematic, however, because of the flow duct guided through the hull. This is because the inflow and outflow openings provided at the end of the flow duct pass through the hull, which is designed to be protected against military threats, and therefore said hull is weakened and there is an increased risk of injury to the individuals accommodated within the hull. For example, the clouds of gas which are released during an explosion of a mine and are frequently also referred to as a blast can penetrate the interior of the flow duct with very great energy and can result there in considerable damage including even complete tearing off of the flow duct. In the worst case, the clouds of gas can also penetrate the protected interior of the vehicle, which means a considerable potential of danger to the crew.